Propeller



Feb, 20, 1923.

R. c. JACKSON PROPELLER Filed July 5,` 1921A lnverzor Patented Feb. 20, 1923.

NITE'D sr RQIBRT CATTLEY J'CKSON, 0F CALGARY, ALBERTA, CANADA.

PROPELLEB.

Application mea my 5, i921. serial No. 4s2,4so.' j i l' To all whom t may concern.

Be it known that I, ROBERT CA'rrLEY J ACK# soN, a subject of the King of Great Britain and Ireland, and a resident of Calgary, in

5 the Province of Alberta, in the Dominion ofv Canada, have invented certain new and useful Improvements in Propellers, of which the followlng is a specificatlon.

My invention relates to improvementsin propellers the objects of which are to prevent radial dispersion and reduce surface friction by the application of suitable cutting and controlling devices to the blades of the propeller. In order to reduce surface friction the said devices are so designed that the channels formed between them will be in the form of venza contractae which for- 1 mation will induce a differential velocity of flow across the propeller blades.

It is generally accepted that the rotation of a propeller in an unstable medium such as air or water causes a dispersion of the said I medium towards the periphery, the amount of such dispersion and friction being a.

function of the speed of rotation and the pitch of the propeller driving face. The driving efficiency of a propeller being decreased by the dlspersion of the medium towards the periphery it would appear to be necessary to control this dispersion by the application of fins, ribs, or vanes, to the driving faces of the propeller and arranged in such manner as to guide the flow of the.

medium in the required direction.

It would appear to be a simple matter to attach or form fins, ribs, or vanas upon the driving face of the .blades of propellers to bring about the desiredresults, and several attempts have been made with this end in 40 view. It h`as been found that this can only be success-fully accomplished by careful design based upon the application of scientific principles. The surface friction must be reduced by the induction of a differential velocity of flow of the medium and in such manner that the medium shall not receive too positive a grip from the fins, ribs, or vanes which might result in the propeller carrying around with it a `'quantity of the medium thereby adding to theweight and the frictional resistance of the propeller without increasing its efficiency.

In the accompanying drawings similar characters refer to similar. parts throughout the several views.

Fig. 1 is a plan viewof the blade of a propeller fori use in water. v. l

Fig. 2` is an end view of the same blade showing in broken lines a vane or rib in y section. c v

c Fig. 3 is a side view of `the same blade. .Fig. 4 is a plan'view of the blade of an arr propeller.

Flg. 5 is a side yview of the same blade.

Fig. 6 shows a series of cross sections through the propeller blade showing fins, ribs or' vanes in broken lines.` g

In the design of propeller blades, for either marine or air propulsion, in addition to all other considerations the pitch or dip plays an important part. At thefcentre of rotation the circumferential distance travelled is less than at the periphery and consequently if the pitch or dip were equal the whole length .of the blade the amount of work done at the periphery would beV considerably in excess of that at the centre of rotation. In order to distribute the work done the pitch or dipof the propeller' is greatest near its centre and decreases towards the periphery. The effect of this variation not only distributes the work done but tends to diffuse the medium towards the periphery which diffusion I desire to limit and control. .The formation of channels such as those illustrated accomplishes this result, the blades (a) having mounted or formed thereon specially shaped ins, ribs, or vanes (5); the fins, ribs, or vanes illustrate 'a cutting device (o) at the .front or driving edge of the propeller blade forming a tapering channel between said fins, ribs, or vanes terminating in a throat (d) and then expanding towards the following edge (e). In the drawings the central axis of each rib or vane (b) is' shown concentric, and their outer edges are shown eccentric, to the centre of rotation, but I do not desire to limit myself to the use of the fins, ribs, or vanes, in the actual position shown thereon.V The auxiliary fins, ribs or vanes are to be so arranged relatively to one another as to form venae contractae producing, in the flow of the medium through each of them, the well known Venturi effect thus causing a-differential velocity of flowof the medium across the surface of propeller blades. The differential velocity of fiow of the medium obtained in the foregoing manner will bring about considerable reduction 110 in skin or surface friction, not only on the auxiliary tins, ribs, or Vanes but' also 0n the working surface of the propeller. rlhe height and position of these ns, ribs or vanes should be such that the Work done will be distributed uniformly over thevpropeller blades.

What l do sire to secure by Letters Patent, 1's,

l. ln combination With a means for cutting, and controlling the of, the medium in which it rotates, such means consisting of a plurality of auxiliary lins, ribs or'vanes projecting substantially perpendicularly t0 the' driving faces of the propeller blades and so shaped and arranged claim as my invention,`and de-A propeller oflow Y that they will form channels on such driving faces substantially in the form ovenae contractae. i

2. ln combination with va propeller of means for inducin a di'erential velocity of ilow of the me lum across the faces of the propeller blades which said differential yelocity is produced by the medium passlng along channels between the s ecially shaped fins, ribs, or vanes forme or secured upon the tially as describe v ROBERT GATTLEY JACKSON. Witnesses:

WILFRID J. GRAY,

ERIC L.

ropeller blades substan 

